A new design for projectile bodies in recent years includes a section of the metal casing recessed below the normal surfaces of the projectile body diameter. The recessed area is wound with glass fibers which have been pre-wetted with resin to a level above the adjacent projectile body surfaces followed by curing. The winding is accomplished by passing the glass fibers through a dip tank containing the resin binder prior to winding it around the recessed area on the projectile body. Most excess resin is removed from the glass fibers during the winding process.
In order to prevent unwanted contact of the resin with all other parts of the projectile body, the area above and below the recessed area must be completely masked.
After completion of the winding with the resin impregnated glass fibers, the projectile body is transferred to a curing oven to cure the resin. Since a smooth surface is necessary for avoidance of ballistic problems, the glass fiber resin impregnated area requires machining on a lathe or grinding after cure. This is necessary to reduce the diameter of the resin glass fiber wound area so that it corresponds to a specific diameter within a tolerance of 0.020 which is less than the existing diameter of the adjacent portions of the projectile body.
The above process suffers from several drawbacks, including the fact that the final machining on the lathe or grinder often damages the surface of the glass-resin laminate and/or the phosphated coating on the projectile body casing. This requires refinishing of the metal surfaces or removal and replacement of the fiber-resin laminate. Also, in order to fulfill the mechanical and physical requirements, it is necessary to machine off approximately 30% to about 40% of the glass fiber resin material after cure. This results in increased cost.
In addition, the process has proved to be excessively time consuming as well as costly due to the separate steps required in the masking, machining, mask removal, and refinishing of the projectile body.